Non-dewetting porous membranes

Patent metadata

Field	Value
Publication number	US-10179842-B2
Application number	US-201615010282-A
Country	US
Kind code	B2
Filing date	Jan 29, 2016
Priority date	Apr 6, 2009
Publication date	Jan 15, 2019
Grant date	Jan 15, 2019

Abstract

Microporous membrane composites that are non-dewetting are disclosed. These microporous membrane composites are wet with solutions of methanol and water and are non-dewetting following autoclave treatment in water. The microporous membrane composites comprise a microporous membrane support that is coated with a crosslinked ionomer comprising hydrophilic groups. Compared to the microporous membrane support, the microporous membrane composite has a flow loss on average in isopropyl alcohol of less than 82%.

First claim

What is claimed is:

1. A microporous membrane composite comprising:
a microporous membrane support comprising a crosslinked fluorinated ionomer coating on the surfaces and pores of the microporous membrane support, wherein the fluorinated ionomer coating comprises units from copolymerization of:
i) tetrafluoroethylene;
ii) fluorinated monomer units containing ethylenic groups and functional groups chosen from SO 2 F, —COOR, —COF or combinations of these, wherein R is a C 1 to C 20 alkyl radical or a C 6 to C 20 aryl radical;
iii) monomeric units deriving from a bis-olefin, chosen from formulae (OF-1), (OF-2), or (OF-3) where:

wherein j is an integer between 2 and 10, and R1, R2, R3, R4, individually equal or different from each other, are H, F or C 1 to C 5 alkyl or (per)fluoroalkyl group;

wherein each of A, equal or different from each other and at each occurrence, is independently F, Cl, or H; each of B, equal or different from each other and at each occurrence, is independently F, Cl, H or ORB, wherein RB is a branched or straight chain alkyl radical which can be partially, substantially or completely fluorinated or chlorinated; E is a divalent group having 2 to 10 carbon atom, optionally fluorinated, which may be inserted with ether linkages;

wherein E, A and B have the same meaning as above defined; R5, R6, R7, independently equal or different from each other, are H, F or C1-5 alkyl or (per)fluoroalkyl group; and
iv) a compound having the formula R f (I) x (Br) y , wherein where R f is a fluoroalkyl or (per)fluoroalkyl or a (per)fluorochloroalkyl group having from 1 to 8 carbon atoms, and wherein x and y are integers from 0 to 2, with 1≤x+y≤2;

wherein the fluorinated ionomer coating has an equivalent weight of between 380 g/eq and 620 g/eq,
wherein the fluorinated ionomer coating is between about 25 weight percent and about 30 weight percent of the microporous membrane composite,
wherein the microporous membrane composite has a permeability of about 876 l/atm*hr*m 2 to about 2852 l/atm*hr*m 2 at 22.5° C. measured on 47 millimeter diameter microporous membrane composite samples, and
wherein the microporous membrane support has a rated pore size of 0.2 microns or less.

2. The microporous membrane composite of claim 1 , wherein the microporous membrane composite has an ion exchange capacity of 95 nanomoles/cm 2 or more.

3. The microporous membrane composite of claim 1 , wherein the microporous membrane support is a multilayer membrane.

4. The microporous membrane composite of claim 1 , wherein the microporous membrane composite has a mean densitometer value determined by densitometer readings of a methylene blue dye stained sample of said microporous membrane composite, said mean densitometer value is within ±9% of a mean densitometer value determined by said densitometer of said methylene blue dye stained microporous membrane composite after 4 or more hours flow through contact with isopropyl alcohol containing 5000 ppm fluorosurfactant at a temperature of between 70° C. and 80° C. at a flow rate of at least 80 ml/min through a 47 millimeter diameter sample of said methylene blue dye stained microporous membrane composite.

5. The microporous membrane composite of claim 1 , wherein the microporous membrane composite has a mean densitometer value determined by densitometer readings of a methylene blue dye stained sample of said microporous membrane composite, said mean densitometer value does not differ at the 95% confidence limit by a Student-t test from a mean densitometer value determined by said densitometer of said methylene blue dye stained sample of said microporous membrane composite after 4 or more hours flow through contact with isopropyl alcohol containing 5000 ppm fluorosurfactant at a temperature of between 70° C. and 80° C. at a flow rate of at least 80 ml/min through a 47 millimeter diameter sample of said methylene blue dye stained microporous membrane composite.

6. The microporous membrane composite of claim 1 , wherein the microporous membrane support has pores 0.1 micron or smaller.

7. A method of making a microporous membrane composite, comprising:
a) coating a microporous membrane with a fluorocarbon liquid composition comprising a fluorocarbon liquid medium containing a fluorinated ionomer dissolved or dispersed therein to thereby form a coated microporous membrane composite, the fluorinated ionomer having iodine and/or bromine atoms at a terminal position, at least 90% by weight of the fluorinated ionomer consisting in particles of size lower than 200 nm, wherein the fluorinated ionomer comprises units from copolymerization of:
i) tetrafluoroethylene;
ii) fluorinated monomer units containing ethylenic groups and functional groups chosen from —SO 2 F, —COOR, —COF or combinations of these, wherein R is a C 1 to C 20 alkyl radical or a C 6 to C 20 aryl radical;
iii) monomeric units deriving from a bis-olefin, chosen from formulae (OF-1), (OF-2), or (OF-3) where:

wherein j is an integer between 2 and 10, and R1, R2, R3, R4, individually equal or different from each other, are H, F or C 1 to C 5 alkyl or (per)fluoroalkyl group;

wherein each of A, equal or different from each other and at each occurrence, is independently F, Cl, or H; each of B, equal or different from each other and at each occurrence, is independently F, Cl, H or ORB, wherein RB is a branched or straight chain alkyl radical which can be partially, substantially or completely fluorinated or chlorinated; E is a divalent group having 2 to 10 carbon atom, optionally fluorinated, which may be inserted with ether linkages;

wherein E, A and B have the same meaning as above defined; R5, R6, R7, independently equal or different from each other, are H, F or C1-5 alkyl or (per)fluoroalkyl group; and
iv) a compound having the formula R f (I) x (Br) y , wherein where R f is a fluoroalkyl or (per)fluoroalkyl or a (per)fluorochloroalkyl group having from 1 to 8 carbon atoms, and wherein x and y are integers from 0 to 2, with 1≤x+y≤2;
wherein the fluorocarbon liquid medium comprises a mixture of perfluoropolyethers, said perfluoropolyethers having the general formula F 3 C—O—[CF 2 —CF(CF 3 )—O] n —[CF 2 —O] m —CF 3 wherein m and n are integers, being n>0 and m≥0, said perfluoropolyethers having molecular weight between 300 atomic mass units (amu) and 600 amu, said mixtures having prevailing average boiling points between 55° C. and 135° C. and an average ratio between the indexes m and n (m/n) below 0.05;
wherein the fluorinated ionomer has an equivalent weight of between 380 g/eq and 620 g/eq, and

b) crosslinking the coated microporous membrane by heating the coated microporous membrane to form a coated, crosslinked microporous membrane composite;
wherein the fluorinated ionomer coating is between about 25 weight percent and about 30 weight percent of the microporous membrane composite,
wherein the microporous m

Assignees

• Entegris Inc
• Solvay Solexis Spa

Inventors

• Gjoka Alketa
• Raman Ven Anantha
• Gebert Matthias
• Oldani Claudio
• Ghielmi Alessandro

Classifications

• C08J2327/18

  Homopolymers or copolymers of tetrafluoroethylene · CPC title

• B01D67/0006

  by chemical reactions (in-situ polymerisation, polycondensation, cross-linking or reaction for manufacturing composite membranes B01D69/125) · CPC title

• B01D71/32

  containing fluorine atoms · CPC title

• B01D2325/36

  Hydrophilic membranes · CPC title

• B01D2323/30

  Cross-linking · CPC title